In the manufacture of structured hollow profiles using discontinuous methods, for example by means of U-O forming or by using a rolling-in technique, supporting cores are needed which correspond as far as possible to the inner contour of the hollow profiles. The supporting cores must be able to withstand the forming forces during the molding of the plates without significant deformation, in order to allow accurate forming of the inner contour of the hollow profile. Curved hollow profiles or hollow profiles with varying cross-sections no longer allow the use of a rigid supporting core. While supporting cores consisting of an elastomer are able to support the full surface of the inner contour, they are only able to withstand the great forming forces to a limited extent. Especially, locally occurring, very high surface pressings are a problem here. A further problem with supporting cores consisting of an elastomer is that the bending capability of the elastomer drops with increasing hardness, so that either problems arise when pulling the core, due to the reduced bending capability, or the shape retention following insertion of the supporting core is incomplete. Finally, it must be mentioned that wear of the elastomer allows only small numbers of structured hollow profiles to be produced before they need to be replaced.
From German published application DE 30 00 170 A1, a core is also known for use during pipe bending, which comprises a plurality of interconnected supporting members. The problem with this core is that it has a relatively complex design and does not allow full-surface support, as is required for the production of structured hollow profiles.